Resizing window while on Roadmap page no longer refreshes the Roadmap rendering

Summary

Roadmap rendering currently works on absolute sizing of timeline, hence resizing browser window causes Roadmap to re-calculate rendering logic. But this has seems to be stopped from working, leading to Roadmap being cut-off when window is resized.

This is happening due to changes introduced in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/10419.